ARM: dts: am33xx: Update DCAN nodes

Add "raminit-syscon" property to specify the RAMINIT register.
Add clock information.
Rename can nodes from "d_can" to "can" to be compliant
with the ePAPR specs.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>